Industrial lift truck



Sept. 16, 1941. w. P. BOMAR 2,256,454

INDUSTRIAL LIFT TRUCK Filed Feb. 18, 1941 2 Sheets-Sheet l m? Z0 a l I '1 I I1 i E 7 i W l 11 lo INVENTOR MAL/AMPflO/VAP BY 9 ?2Z ATTORNEYS Sept. 16, 1941. w, BOMAR 2,256,454

INDUSTRIAL LIFT TRUCK Filed Feb. 18, 1941 2 Sheets-Sheet 2 A k 2 x k INVENTOR Patented Sept. 16, 1941 UNITED STATES PATENT OFFICE,

INDUSTRIAL LIFT TRUCK William P. Bomar, Fort Worth, Tex. Application February 18, 1941, Serial No. 379,464

12 Claims.

This invention relates to improvements on the lift truck structure shown in my copending application Serial No. 341,095, filed June 18, 1940. Its purpose is to do the work of that apparatus and perform additional work. Its purpose also is to provide some structural features which are particularly useful in some of the work to be done by the main combination.

Generally speaking, my improved structure is made as a power operated machine to lift a platform loaded, for example, with a pile of flour bags, to carry it to a place for unloading, and to unload the pile without the platform, while maintaining the pile formation. It is useful in loading freight cars at mills when it is not desired to include the platforms. This is one illustration of specific utility. The features of my invention may be built into different types of industrial lift trucks. Such trucks are generally used inside industrial plants and warehouses. So far as I know, however, none of them have embodied mechanism to carry out my new operations. The platforms used with these kinds of trucks generally are made to hold their loads but a few inches above the floor.

I will disclose the pertinent features of the invention with reference to the accompanying drawings. It should be understood, however, that the structure indicated is to illustrate a form of the invention. equivalent machinery may be made in different forms having the same functions and adapted to the same or different commercial forms of lift trucks. I

In the drawings:

Fig. l is a side view showing generally a power lift truck and the elements which make a new combination with the truck; this view does not show the load on the platform;

Fig. 2 is an end view of Fig. 1, showing one type of platform; this view does show the load on the platform and in the form of piled bags;

Fig. 3 is a detail view on an enlarged scale of a portion of Fig. 2, but with the platform and its load out of the way, so as to show the position of platform gripping means;

Fig. 4 is a top plan view of the unloaded platform with parts broken away to show the platform gripping devices and an indication of their operation with relation to the platform;

Fig. 5 is a detail view indicating a different position, from that of Fig. 3, for the hydraulic cylinders on the truck;

Fig. 6-is a fragmentary plan view of another From this disclosure,

form of mechanism to operate the platform gripping devices of Fig. 4;

Fig. 7 is a detail view of a modified means for engaging the truck and platform; and

Fig. 8 is a view of a modified form of platform arranged as an element chinery under special conditions.

To disclose my invention I have indicated as part of my new combination a commercial form of industrial power lift truck. This form is the Elwell-Parker truck such as used in transporting flour bags, bran bags, and the like. Other truck forms and other uses will be clearly embraced within the main plan of my invention.

The main plan is to combine means, in one power truck mechanism, to carry out these advantages and operations: To retain the prior art advantages in successively picking up platforms supporting a neatly piled load, such as flour bags, in carrying them from one place to another for deposit in a new location; and in addition to make it optional with the truck ,driver whether to deposit the platform with the load on it or to deposit the load of piled bags quickly at the new location but without the platform. A difficulty of depositing the load without the platform is to carry out the operation by power and without losing the desired formation of the bags or other piled units. Heretofore, such units have been taken ofi the platform by hand and repiled. A main feature of my invention is to unload the platform by power and without repiling. A main advantage is that the piles on platforms may be taken from the place of. storage and deposited rapidly in freight cars, but

without the platforms. This operation saves much time and labor. Another feature of my invention is 'to carry on the power truck operation just mentioned so as to stack one pile on another pile. Thus, the piles may be deposited both side by side or one on top of the other, all without the platforms. One result is that substantially the whole volume of a freight car can be loaded quickly from the warehouse. So far as I know, I am the first to provide power mechanism to carry out either of these. particular operations, namely, the simple deposit of the pile formation without the platform or such deposit with one pile on top of another in successive truck operations.

In addition to the broader features of the invention, I will disclose several very helpful specific features related to the main ones.

Having the above in mind, the structure as illustrated will be made clear. Referring to Fig.

of the unloading ma- 1, the general power mechanism and operation of an industrial lift truck are very well known. I will mention these briefly. The driver stands on the end platform in booth I. He steers the truck by wheel W. Alongside of this wheel within easy reach around the booth he has at hand the power control devices or switches, not shown. Power is furnished by batteries inbox 2. Motors are connected to the driving wheels, the winch 3, and the elevator tilting or rack bars 4. Most of the elevating or lift mechanism is mounted in the vertically arranged cage or frame 5.

Elevator frame 5 is pivoted on the truck frame at bearing 6, one on each side. Part way up, fram 5 is pivoted to rack bars 4, one on each side. These are engaged by pinions operated from a motor I above box 2. The driver controls the motor to swing the frame 5 to vertical or tilted position. It is normally held vertical. In either position a motor for winch 3, under the drivers control, will wind or unwind chains 9 over sprockets associated on the elevator parts. The elevator has a strong movable sub-frame assembly mounted in frame 5. This includes the vertically arranged plate l seen in front of frame 5, Fig. 3. This vertical plate has horizontal fork. members II at the bottom. They are spaced and adapted to extend under the platform I2 between its skids or supports at each side. As the elevator is raised or lowered the platform l2 may be lifted, carried, and deposited on the floor or other support by these forks II. The truck is driven up to the platform so the forks are positioned for lifting (Figs. 1 and 2). The platform may be lifted, for example, to any height on the line a-b, Fig. 1. All this is well known in lift trucks. The truck so far specifically referred to is one that will lift, transport, deposit, and also stack unit loads with their platforms. The parts G in Fig. 1 indicate the driving, braking, and steering mechanism or truck running gear. All this mechanism. indicates what I referred to as a commercial form of Elwell- Parker truck. It is a well known form in commercial use. An example in the prior patented art of another industrial lift truck is Gfrorer 1,896,543 of 1933. But neither the commercial nor prior patented form of lift lruck embodies the means, mechanism and devices, which I will now refer to in my disclosure.

Carried at each side of elevator plate It) to move with it, Figs. 1 and 3, are strong horizontal supports l3. They are rigidly supported and braced, so as to carry weight and might be and act as if they were integral parts of plates In, which is a big strong casting. These supports extend from one side as the weight-carrying prongs ll extend, from the opposite side of plate 10. They all move as a unit when chains 9 raise and lower plate l0. v

On supports I3 I mount hydraulic cylinders H, one on each support, see Fig. 3. Piston rods l5 extend from these cylinders, are provided with blocks It at their ends. The blocks support the pusher or load holding frame II. This may conveniently be made of piping to make it very strong without excessive weight.

The purpose of the cylinders, pistons, and frame is to provide an unloading means for platform or pallet l2. The hydraulic power cylinders may be operated by oil or other fluid. I provide, see Fig. 1, spaced U supporting frames I8-with legs fastened on lower supports l3. These frames 18 straddle other parts. At the top, It has a table support for motor-operated oil pump I9 and valve box 20. Pressure and exhaust pipes 2| lead down the legs of a frame I8 to opposite ends of pistons in cylinders ll. All these parts just mentioned are supported by and travel with the elevator part ID as it is raised and lowered. It should be understood that a suitable remote controlled valve in box 20 operates under the control of the operator, when desired to open and close the inlet and outlet passages to cylinders l4 to move their pistons in unison as and when desired, The piston rods l5 carrying frame I! have a controlled power movement across the top of platform I2 and back again, see Fig. 1. The parts supported at top of frames l8 and on their lower supports I3 result in the following condition. Frame .11 can operate at any of the elevations to which platform I2 may be held at rest by fork members II and in the desired relation to the platform. This means that a power lift truck of the tiering type is operable in my new combination for the new result in unloading a pile of units.

It will be seen from the arrangement of Fig. 1 that electrical devices I have mentioned as carried by frames I8 are conveniently supplied with current through wires in flexible cable 22. This cable winds and unwinds from a spring operated take-up reel 23 mounted above battery box 2. The electrical connections and details are not shown as any electrician can make them from this disclosure. For example, it will be understoodv that the remote controlled valve in box 20 has a suitable control switch adjacent wheel W for the truck drivers convenience. There is also a switch there for the motor of pump l9. As the elevator moves up and down, cable 22 maintains electrical connections for those electrical devices also moving up and down. The cable wires are connected from the reel 23 to the points of devices mentioned, the latter being relatively stationary and not moved with the elevator. And the truck driver conveniently controls their operations by the controls at his hand.

An additional electrical device movable with those previously mentioned as going with the elevator, is solenoid 24, not seen in Fig. 1 but shown in Fig. 3. Its main purpose is to give power operating service to mechanism for gripping the platform and thus fastening it to the elevator, during load manipulating operations.

The electric switch energizing solenoid 24 is preferably actuated in conjunction with the switch for the valve in box 20. This means that the hydraulic valve and the gripping mechanism are operated simultaneously. Of course these devices could be operated independently of each other but I have found it of convenience to decrease the number of controls that must be manipulated by the operator. And it is desirable to have the gripping mechanism acting whenever frame I! is power operated. My simultaneous controls when interlocked provide for satisfying this desire.

The platform gripping -means is indicated in Figs. 3 and 4. As shown, it consists of two grab hooks 25, pivoted on rigid bar 26 mounted between forks l I. At adjacent ends of 25 rigidly mounted cam plates 21 extend upwardly, see Fig. 3. Between them are rollers in bearings at the end of a spreading fork'28. The latter is pulled upwardly when solenoid 24 is energized and allowed to drop (as far as seen in Fig. 3) when deenergized. When fork 28 drops, spring 29 moves hooks 25 to positions as in Fig. 4, where, they are stopped by contact with sides of forks II. The top plane of hooks 25 is about the level of forks H so as not to interfere with all the operations desired of these forks.

An example of a different arrangement to actuate hooks 25 is seen in Fig. 6. In this modification a hydraulic cylinder!!! with double acting pistons operates to spread the adjacent upturned ends 21' of hooks 25 apart and clamp the hooks in the hook bars 3|. The cylinder 40 is suitably connected by flexible pipe II to the source of hydraulic pressure operating the pistons in cylinders H. When pressure is built up to operate these pistons of cylinders ll, fluid is forced into the center of cylinder 40, moving the pistons on each side outwardly, thereby pivoting hooks 25 to pallet locking position. On

release of hydraulic pressure the spring 29' returns hooks 25 to the position as shown in Fig. 4. As with the solenoid controls the hydraulic power for cylinder 40 may be arranged, if desired, to operate independently of cylinders H. The simultaneous operation is simply a matter of better operation and control for the truck driver. It is one I prefer.

Platform l2 in one suitable form or construction for my purpose is indicated as resting on the floor in Figs. 1 and 2. Its detail is seen in Fig. 4. Modifications are indicated in Figs. '1 and 8. A platform such as that of Fig. 1 is generally well known. It is called a. pallet, and piled with flour bags. But the ordinary pallet has no means to combine with my mechanism as I want it to do for my purpose. This is the reason' for my additions. Figs. 2 and 4 show the center rib 30, provided on opposite sides with hooks 3|. They are generally arranged like rack bars; as used, they are hook bars. They cooperate with grab hooks 25 and these bars are long enough to insure certain operation in the grab hook engagement. It occurs when solenoid 24 is energized. I prefer to have the hooks arranged so as to cooperate with the grab bars at any position of the latter under the top of the platform, but only a few of these hooks 3| are shown in Fig. 4.

One advantage of my arrangement, by way of example, is: The pile of bags F on platforms [2, Fig. 2, may weigh a ton. My mechanism positions forks II for lifting; the load is then lifted off the fioor, taken to the place of load deposit; the electrical devices controlling operation of the pistons and grab hooks then put them in operation; andwhile the platform is held tightly on the forks II the pile is unloaded, still in pile formation, and deposited in pile formation without the platform. The latter is still combined with my mechanism after the piled load is given a pile deposit. This may be on the floor or at any elevation within range of a tiering truck.

This work is automatically done by my mecha nism in remarkably quick time, with remarkable saving of labor as compared to any prior art way of doing it that I know. Furthermore, it is done with piled goods making very heavy loads and without things going askew in the operation.

I have found some comparative difficulties in handling some loads, for example bags of bran as compared with bags of fiour. My modified platform l2 of Fig. 8 takes care of this. It is substantially like that of Fig. 2 except that outwardly tilting side boards or guiding devices 35 are provided to react on the pile. These shallow side boards 35 cooperate in the whole action and sufllciently improve it where, as in handling bran bags, there is a tendency for the poweroperation to push things askew. The load is steadied at opposite sides of the line of travel in the unloading operation and sluicing the pile of articles with guiding devices prevents tipping and shifting. With this type of pallet more bran bags can be handled in one pile than is otherwise possible.

In Fig. 7 I have merely indicated a simplified means for holding a platform S on my mechanism. A lug, as 36, integral with each fork member II, is lifted into and lowered out of a socketv 31 on the under side of the platform. The latter is then held by the contacting shoulders of lugs and sockets as theload in pile formation is deposited without its platform.

All my platforms preferably are made smooth to facilitate the unloading operation. This is particularly desirable with paper bags. I have not troubled to show the variety-of anti-friction means that may be used on the top platform surfaces. But I contemplate varying them somewhat according to the character of the load and mounting rollers to take the load on the-.

platform. The latter means is desirable whenever extremely easy movement is desired. I have found' their expense is not necessary in the load examples I have given. One mechanism can operate on and serve a large inventory of platforms or pallets. It is desirable to keep down their expense. out that the rapidity of unloading piles of bags from the use of my invention materially lessens the number of platforms needed around a warehouse. Those used in my system are returned sooner for reuse at the loading point of their mill cycle than in the old system.

What I refer to as platforms are commonly called pallets by the users. One result of my operating mechanism may be referred to as a pallet unloading operation. I ordinarily carry it on by depositing the pile with a short fall, the height of the pallet to the floor. When that is the only use the modification of Fig. 5 will simplify my mechanism. In that the power cylinders M are mounted on the bed of the power truck. They do not move up and down with the elevator. The valve box 20 and motor I9 may be mounted on the top of the battery box 2 in a suitable manner. Everything else is substantially the same as in the main construction described except that frame I1 is carried by the piston rods with enough clearance to permit forks H to operate for lifting and lowering the pallet, a short distance of a few inches if the tiering combination is not used. This makes a most inexpensive mechanism for the simplest operating cycle. In the operation, as before described for solenoid 24, the latter moves with prongs II to grab the pallet anywhere the elevator goes to on line ab of Fig. 1. A take-up electric conduit is desirable for that. But if the plan of Fig. 5

is used, even that detail is avoided. So somev I attention to the desired range of adapting my ideas as disclosed should be given according to the work to be done, and expense can be saved by so doing in putting my disclosure into commercial form. In the simplified modification of Fig. 5 a knuckle joint should be provided between frame l1 and the piston rods if the elevator is to be tilted on pivots corresponding to 6 of Fig. 1. It should be clear too that while I have chosen the Elwell-Parker tiering form of lift truck,'using it as part of my new combina- And in this connection I pointtion as specifically disclosed, other commercial types of tiering lift trucks might be used and my mechanism adapted in equivalent forms to get the results in the same ways or their equivalents.

In my above mentioned copending application I describe in some detail the advantages intended, use, etc. of an invention like this one. I need not repeat all there stated. But a brief description of operation by way of examples is desirable here.

In operation the driver of the truck picks up a loaded pallet in the warehouse, drives to a freight car; in going up an incline he tips elevator frame 5 by operation of bars 4, Fig. 1, so as to avoid the pallet hittingthe inclined floor in front. In tipping, my frames it have clearance to tip back as my power cylinders do. When the floor is again level, the frame 5 is again put vertical. The driver has his load inside the freight car. If he wants to deposit on the floor, he does it. If the floor is already piled but not to the roof, he deposits on previous piles. In both cases he has a power operation to unload the pallet, without losing pile formation, and

he drives out of the freight car with the pallet on the truck.

The unloading operation as in my copending application may be characterized as a holding of the load in a stationary position while the truck is backed away from the pile and the prongs are withdrawn with the pallet from underneath the load. I have found it preferable sometimes to reverse the truck movement through its driving mechanism, as the pistons and loadholding frame are-forced forwardly in the opposite direction to the truck drive, so that theload drops vertically into the position to which the truck has conveyed it. In this way, with extremely heavy loads the operation of unloading the pile is conducted with greater ease. In some instances, however, and with certain types of articles, a simple pushing operation with the pistons may be sufficient to unload thepallet. For example the pile is carried against a wall; the truck can then be pushed back by operation of frame l1, and withoutusing the truck's other power, to back off. It will be understood that the mechanism disclosed herein may be adapted for transporting and unloading many types of articles and that the use to which the combination is put will be a matter only of applying the mechanism in the most convenient manner for a particular operation.

Having made my disclosure to the man in this art of industrial lift trucks and their uses, I claim as my invention:

sired to deposit the pallet and its load by lowering both from lifted to deposited position and then withdrawing the truck.

2. The combination of a lift truck and a pallet, said truck carrying means to first move under the pallet and then lift the latter, a load pusher frame on the truck vertically positioned with its lower edge above the pallet when the latter is lifted, gripping devices operable to temporarily fasten the pallet to the truck, power means on the truck to operate the pusher while the pallet is in lifted position, means to drive the truck from one position to another, said combination being arranged to push a pile of units without losing their piled form from the pallet to another supporting surface by operating the pusher to hold the load substantially stationary with respect to the truck while the truck withdraws with th pallet gripped to it.

3. A truck having power devices thereon for lifting, carrying, and depositing loaded pallets,

said truck including an elevator mechanism with its lifting portion insertable under a pallet when it stands independently of the truck, in combina tion with a pallet, clamping mechanism, part on the truck and part on the pallet, to hold the pallet clamped tightly on the lifting portion of said elevator, a vertically arranged load holding member and power means to operate said member mounted on said elevator, and means to actuate that part of the clamping mechanism on the truck and said power means so as to hold said pallet tightly on the elevator whenever said load holding member is actuated.

4. A truck having power devices thereon for lifting, carrying and depositing loaded pallets, said truck including a combined elevating and tilting mechanism with its lifting portion insertl. A power operated truck and pallet adapted I to handlea load of units in piled form on the pallet, said truck having mechanism under the truck driver's control to lift the loaded pallet, carry it to a place of load deposit and deposit theload there while retaining its piled form, either with or without the pallet and at the option of the driver, part of said mechanism for depositing the load without the pallet comprising in combination a vertically arranged pusher, means to move it independently and from one end to the other of the pallet while engaged with the load for pushing, gripping devices arranged in part on the pallet and in part on the truck and operable to hold the pallet locked on the truck while the pusher is working to unload and the able under a pallet when standing independently of the truck, in combination with a pallet,

clamping mechanism, part on the truck and part on the pallet, to hold the pallet clamped tightly on said lifting portion when desired, and a vertically arranged load holding member mounted on the elevator mechanism so as to be relatively movable across the face of the pallet and horizontally while the latter is clamped on the elevator, power means to operate said load-holding member, said power means and holding member being mounted on the elevator to tiltwith it, the holding member being adapted to hold the load on a pallet from'horirontal movement while the truck backs out to draw the elevator with the clamped pallet from under the load, all constructed and arranged for control by the truck driver whereby the load may be dropped vertically without the pallet.

5. In an'industrial elevator truck of the type adapted to lift, transport and deposit loaded pallets one by one and having elevating mechanism and means for tilting the latter, the combination' of means for withdrawing the pallet from underneath a load placed thereon, said means including a support rigidly attached to said elevating means and vertically movable with aontal movement whenever the hydraulic mechanism is operated.

6. An industrial truck having power devices to lift, carry and deposit loaded pallets one by one and including a load lifting and tilting elevator with its lifting portion insertable under a pallet when standing independently of the truck and means mounted on said truck to deposit a load without the pallet, said means comprising a latching mechanism fixed on the elevator and adapted to grip the pallet, a vertically disposed unloading frame and hydraulic mechanism attached thereto and to the elevator,

said hydraulic mechanism being adapted to push said unloading fram horizontally crosswise of the load on a pallet when the latter is gripped by said latching mechanism, and control means for the latching and hydraulic mechanisms so that they may be simultaneously operated.

"I. An industrial elevator truck of the type adapted to lift, carry and deposit loaded pallets; in combination with a pallet, the latter having means for the reception of gripping members carried by the truck, pping members pivotally attached to the truck, mechanism on said truck to engage adjacent ends of the members and operate the same, said mechanism including a solenoid, means to energize the solenoid, a cam bar operable thereby when energized to spread said adjacent ends and pivot said members to pallet gripping position, and means to maintain said members in inactive position when the solenoid is inactive.

8. An industrial elevator truck of the type adapted to lift, carry and deposit loaded pallets; in combination with a pallet having means for the reception of gripping members carried by the truck, gripping members pivotally attached to the truck, mechanism on said truck to engage adjacent ends of the members and operate the same, said mechanism comprising an hydraulic cylinde having double acting pistons, means to actuate said pistons and spread the adjacent ends of said members into pallet gripping position, and means connecting the gripping members to them in inactive position when said pistons are inoperative.

9. In a truck having power devices thereon for lifting, carrying and depositing loaded pallets and having an elevator frame and mechanism,

witli'means to tilt said frame, an unloading appaiatus to deposit a load piled on the pallet without leaving the pallet underneath said load, said apparatus comprising supports on each side of said frame, hydraulic piston cylinders carried on said supports, an unloading frame attached to said pistons and movable horizontally by said pistons across and above the face of a pallet,

at any height to which a pallet is elevated, in-

verted U-shaped frames mounted on said supports and carrying power mechanism to actuate said pistons, means connecting the power mechanism with the cylinders, and a cable with a take-up reel attached to the truck forming the connection with the driving booth or said truck,

said truck also having releasable pallet gripping means to hold the pallet against movement with the load whenever said pistons are actuated.

, 10. In an industrial power lift truck such as used to pick up, transport, and deposit loaded platforms, the combination of the usual truck lift mechanism and power-operating means therefor, a load supporting platform or pallet separable from said mechanism, latching mechanism to hold the platform on the lift mechanism, pusher mechanism operable to push a load oif the platform while the latter is latched to the lift mechanism, and guiding devices located to steady the load at opposite sides of the line of travel of said pusher mechanism whereby a load comprising a pile of separate articles may be pushed simultaneously off a platform and deposited without substantial disturbance of the pile formation as by tipping and shifting.

11. A truck having power devices thereon for lifting, carrying, and depositing loaded pallets, said truck including an elevator mechanism with its lifting portion insertable under a stationary pallet when standing independently of the truck, in combination with a pallet, clamping mechanism, part on the truck and part on the pallet, to hold the pallet clamped tightly on said lifting portion when desired, and a vertically arranged load-holding member mounted on the elevator mechanism so as to be relatively movable across the face of the pallet and horizontally while the latter is clamped on the elevator, power means to operate said load-holding member, said clamping mechanism, said load-holding member, and associated power means being vertically movable with said elevator mechanism to any level desired, the power means being adapted to hold the load on a pallet from horizontal movement while the truck backs away to draw the elevator with the clamped pallet from under the load at any level within the range of the elevator, all constructed and arranged for control by the truck driver whereby the load may be dropped vertically without the pallet.

12. A truck having power devices thereon for lifting, carrying, and depositing loaded pallets, said truck including an elevator mechanism with its lifting portion insertable under'a pallet when standing independently of the truck, in combination with a pallet, clamping mechanism, part on the truck and part on the pallet, to hold the pallet clamped tightly on the lifting portion of said elevator mechanism when desired, and a vertically arranged load holding member carried on the truck so as to.be relatively movable across the face of the pallet and horizontally while the latter is clamped on the elevator, power means to operate said load-holding member, and adapted to hold the load on a pallet from horizontal movement while the truck backs out to draw the elevator with the clamped pallet from under the load whereby the load may be dropped vertically without the pallet. 

